apheresis vs excision

apheresis

noun
  • The removal of blood from a patient, and the removal of certain components (such as platelets) from that blood, followed by the transfusion of the filtered blood back to the donor (patient). 

  • Elision, suppression, or complete loss of a letter or sound (syllable) from the beginning of a word, such as the development of special from especial; procope. 

excision

noun
  • The removal of something (a tumor or body part) by cutting. 

  • The removal of some text during editing. 

  • The removal of a gene from a section of genetic material. 

  • The fact that, under certain hypotheses, the homology of a space relative to a subspace is unchanged by the identification of a subspace of the latter to a point. 

How often have the words apheresis and excision occurred in a corpus of books? (source: Google Ngram Viewer )